Initial results from parallel coil operation of the Coaxial Slow Source field reversed configuration device

Abstract

The Coaxial Slow Source (CSS) is a device in which 'annular' field reversed configurations (FRCs) (small aspect ratio, elongated, toroidal plasmas with poloidal field only) are formed in the space between coaxial coils carrying toroidal currents. The device is constructed so that the plasma can be translated into a simple cylindrical chamber and re-formed as a conventional FRC. Formation of FRCs on slow time-scales (50-250 mu s) at low loop voltage (87.5-700 V) has been demonstrated. The paper presents initial results from the new parallel configuration device CSSP in which the inner and outer coils are connected in parallel to the capacitor banks. The parallel coil arrangement has significantly reduced the contact of the plasma with the walls and thus the impurity content. Configurations with confinement times of 1o-30 mu s, densities of 3*1021 m-3 and temperatures of 3-20 eV are typical. Results are presented on formation, energy balance, a nondestructive tilt instability and dynamics associated with magnetic tearing